Market failure: water prices in Chile do not reflect [enough] scarcity because the value of water (its market price) is too low relative to investment and operation costs. The implication is that water will be overused (and depleted) too quickly, e.g., "in Copiapó (in the desert of Atacama) people irrigate grass lawns and wash sidewalks to reduce dust" :(

This paper comparing efficiency in public & private French water utilities finds (contra their "conclusion") that they are similar, once you consider taxes, debt, and tariff schedules. Regulation matters!